Method for making lead sheathed cables



O 1936. H. A. STAPLES METHOD FOR MAKING LEAD SHEATHED CABLES I FiledApril 23, 1952 wwwxgmm INVENTOR /Yw m w In Patented Oct. 13, 1936 PATENTOFFICE METHOD FOR MAKING LEAD SHEATHED CABLES Horace A. Staples,Piainfleld, N. J., assignor to Habirshaw Cable and Wire Corporation, NewYork, N. Y., a corporation of New York Application April 23,1932, SerialNo. some: 20m ns. (Cl. 207-10) The present invention relates toimprovements in methods for making electrical cables and moreparticularly to improved methods for applying metal sheaths toelectrical cables'to the general end that an improved and morehomogeneous and perfect sheath may be produced than heretofore.

More particularly the present invention relates to improvements in themethod and machine which forms the subject matter of the copendingapplication of William A. Del Mar and-Earle -A. Mitchell, Serial No.601,430, .flled March 28, 1932. According to the aforesaid application,provision is made for minimizing the possibility of the introduction ofundesired oxide into the sheath of a metal cable as the same is formedfrom successive metal charges in an extrusion press.

The present invention has for its object the provision of an improvedmethod for making a 7 metal sheath cable wherein a special atmospheresuch as a reducing or inert gas is introduced into the extrusion pressbelow the ram as the ram is withdrawn, which special gas atmosphereprevents the formation of undesirable oxide upon the top surface of thepreceding metal charge and which special gas atmosphere is alsomaintained'in the metal press during the recharging of the press with anew metal charge so that oxide formation upon the surface of or in thenew lead charge is also precluded.

A further object of the present invention resides in the provision of animproved method for lubricating a lead press prior to acharging-operation whereby subsequent extrusion operations arefacilitated. v

A further object of the present invention resides in the provision of animproved method for making lead sheath cable wherein a reducing or inertgas atmosphere together with a quantity of a lubricating medium may beintroduced into the lead press cylinder prior to the introduction of anew charge of lead therein, which atmosphere and lubricating mediumcooperate to prevent the formation of undesired oxide upon the leadinthe cylinder and which lubricating medium also I 4 serves to lubricatethe walls of the cylinder to facilitate the subsequent extrudingoperation.

Further and other objects of the present invention will be hereinafterset forth in the accom- 50 panying specification and claims and shown inthe drawing, which by way of illustration show what I now consider to bea preferred embodiment'of the invention.

The drawing shows in 55 Figure 1 the improved machine by which the ismodified as will now be described.

drical space i5 between the cableand the inside of the larger diameterdie. The pressure for ex truding the lead sheath is obtained by ahydraulic ram l6 which presses upon a lead chargeil in 1 the cylinder orleadpress chamber i8.

Due to the large amount of lead which has to be used, particularly for acable of even normal length, it is generally impracticable to performthe extruding operation continuously. flit is 20 necessary to 'stop andre-charge the cylinder 18 from time to time and during these re-chargingoperations oxide may be formed upon the surface of'the old lead chargeI! or in the newlead which is being introduced into the cable or uponthe top 25 of the new lead charge. ,Thisnndeslred oxide formation occursdue to the presence or. free oxygen in the air in the cylinder and dueto the heated condition of the lead. Accordingly, im-

perfect cables are produced.

' 30 In order to prevent the formation of the undesirable oxide, whichsubsequently; becomes introduced into the lead sheath of the cableduring the extruding operations, the previous procedure.

35 The ram I6 is provided with a dummy head 22 carried on a stud 23slidably fitting the head of the ram1i6. The stud 23 is interiorlyhollowed out as indicated at 24 and from this hollowed out passage inthe stud ports or passages "extend 40 laterallyasshown. The interior ofthe ram is also provided with a hollowed portion or conduit 26.Connected to the upper portion of the ram and in communication with theconduit portion 26 is a flexible connection 11 which extends to a.three-way valve generally designated 2!. Beyond the three-way valve 28is an atomizing device 29 for atomizing a lubricating medium such as oilwhich is taken into the atomizin'g device 29 from a reservoir 30. 3| isa pipe or condult through which a reducing or other inert gas such asilluminating gas, carbon dioxide, steam or the like is supplied underpressure. Such gas free from free oxygen will hereinafter be termed "aspecial atmosphere.

After one lead charge has been extruded, the plunger or ram head 22 isin contact with the upper surface of the previous lead charge whichsurface is substantially at the bottom of the cylinder l8. With the ramin lower position, the three-way valve 28 is thrown to a. position toadmit a mist of lubricating oil and the reducing or other inert gasthrough the flexible conduit 21 into the interior of the ram. The ram isthen raised and the mist of oil and reducing gas is sprayed on the wallsof the chamber or lead press cylinder as the ram is withdrawn upwardly.It

will be understood that the dummy head 22 on the ram drops and allowsthe mist to flow laterally to the walls between the upper part of thedummy head and the lower part of the plunger ram. The gas andlubricating medium passes around the dummy head and down into the spacebetween the top of the previous lead charge and the ram, as the ram iswithdrawn upwardly. In this way a reducing atmosphere or inert gasatmosphere is maintained in the chamber or space above the old leadcharge between the upper surface thereof and the ram as the ram is beingwithdrawn. The lubricating medium sprays the bore of the lead press withoiLpreVenting sticking of the ram and facilitating the subsequentextruding operation.

The next step in the operation is to fill the chamber of the metal presscylinder or container with a new charge of metal such as lead. Suchmetal, for example molten lead, is introduced into the chamber orcontainer of the extrusion press through a removable pipe 32 which leadsto a lead pot or lead pump or other source of metal supply. The pipe 32during the filling operation, is extended down into the specialatmosphere in the container. After filling such pipe 32 is removed.During this filling operation the three-way valve 28 is shifted to aposition to shut off further supply of gas and lubricating medium and toestablish communication between conduit 21 and a pipe 33. Pipe 33 mayextend directly to atmosphere or it can extend into a water sealindicated by dotted lines at 3!. The lead is then introduced into thechamber and the reducing gas atmosphere is gradually displaced anddischarged through pipe 33. During the filling operation it will beappreciated that the reducing gas or other inert atmosphere within thechamber i8 prevents oxidation of the lead either in the new lead charge,which is introduced in a molten state, or upon the top surface of theold lead charge I1. I

The machine is then ready for the subsequent extruding operation. Duringthe extruding operation the three-way valve is shifted to closedposition and extrusion proceeds in the usual manner.

By the above procedure oxygen is prevented from reaching the surface ofthe old lead charge or the molten lead while such lead is being initroduced into chamber l8. The reducing gas or inert gas which wasintroduced in the chamber or cylinder of the lead press upon upwardwithdrawal of the ram prevents oxygen from the air from entering thechamber and precludes oxide formation.

Furthermore the lubricating medium supplements the reducing or inert gasupon being high- 1y heated since such lubricating medium under heatitself becomes converted into hydro-carbon gas which has reducingcharacteristics.

Figure 2 shows a modified form of ram. With this form the supplementalor dummy head 22 is dispensed with and in'lieu thereof the ram l6a is soshaped that its lower integral portion constitutes the head. An interiorconduit 26a is provided as before and openings or passages 25a extend tothe periphery of the ram. Preferably a closing plug 40 is provided inthe lower face of the ram l6a. With this construction the gas which issupplied under pressure to conduit 26a escapes into the space below theram upon withdrawal of the ram by passing from passages 25a around theedges of the lower end of the ram. The diameter of the lower end of theram permits such gas flow. With the construction shown in Fig. 1 thediameter of the supplemental or dummy head is such as to provide forsuch gas flow upon upward withdrawal of the ram.

What I claim is:

l. The method of making metal sheathed cable which supplements the usualsteps of the extrusion process by the step of introducing a specialatmosphere into the extruding chamber while the press ram is in thechamber and is being withdrawn therefrom and by such special atmosphereat all times entirely preventing the introduction of free oxygen intothe extrusion chamber to thereby preclude the oxidation of the metalduring the step of filling the chamber with metal, and utilizing thespecial atmosphere to introduce lubricant into the chamber.

2. The method of making metal sheathed cable which supplements the usualsteps of the extrusion process by the step of introducing a specialatmosphere through the press ram and into the extruding chamber whilethe press ram is being withdrawn therefrom and by such specialatmosphere at all times entirely preventing theintroduction of freeoxygen into the extrusion chamber to thereby preclude the oxidation ofthe metal during the step of filling the chamber with metal.

HORACE A. STAPLES.

